Pressure sensitive recording system and method of providing a split image therefor

ABSTRACT

Corresponding images (an image and a mirror image thereof) are provided on adjacent surfaces of two sheets. An encapsulated liquid reactant precursor is supported on one of the surfaces and a co-reactant is coated on the other surface. The adhesion/cohesion characteristics of the co-reactant coating are so adjusted and selected that upon pressure-effected rupture of the particular capsules used, some of the co-reactant (as well as some precursor) physically transfer and the balance of each remains in situ and does not transfer. Substantially identical chemical reactions are thus produced concurrently on both adjacent surfaces to provide corresponding colored images thereon. If the upper one of the sheets is translucent, as in a typical gasoline credit set, the mirror image formed on the underside thereof by one of the chemical reactions will be viewable from the top side thereof as a right-readable image upon separation of the sheets.

United States Patent Jablonski et a1.

Oct. 1, 1974 PRESSURE SENSITIVE RECORDING SYSTEM AND METHOD OF PROVIDING A SPLIT IMAGE THEREFOR [75] Inventors: Richard B. Jablonski, Lambertville;

John J. Kotla, Mercerville; James F.

Martone, Somerville, all of NJ.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: July 26, 1972 [2]] Appl. No.: 275,394

[52] US. Cl. 117/361 [51] Int. Cl. B4lc 11/06 [58] Field of Search 117/362, 36.1, 36.3

[561 References Cited UNITED STATES PATENTS 2,588,572 3/1952 Potteiger 117/361 2,810,661 10/1957 Newman et a1 117/361 2,872,863 2/1959 Newman et al 117/362 3,020,171 2/1962 Bakan et a1 117/362 3,088,028 4/1963 Newman 117/361 3,241,996 3/1966 Haas 117/362 3,287,154 11/1966 Haas 1l7/36.2

3,558,341 l/1971 Phillips 117/362 3,697,323 10/1972 Brown et a1. 117/362 Primary Examiner-Michael Sofocleous Assistant ExaminerBernard D. Pianalto Attorney, Agent, or Firml-Ienry E. Otto, Jr.

[57] ABSTRACT Corresponding images (an image and a mirror image thereof) are provided on adjacent surfaces of two sheets. An encapsulated liquid reactant precursor is supported on one of the surfaces and a co-reactant is coated on the other surface. The adhesion/cohesion characteristics of the co-reactant coating are so adjusted and selected that upon pressure-effected rupture of the particular capsules used, some of the coreactant (as well as some precursor) physically trans fer and the balance of each remains in situ and does not transfer. Substantially identical chemical reactions are thus produced concurrently on both adjacent surfaces to provide corresponding colored images thereon.

If the upper one of the sheets is translucent, as in a typical gasoline credit set, the mirror image formed on the underside thereof by one of the chemical reactions will be viewable from the top side thereof as a right-readable image upon separation of the sheets.

7 Claims, 2 Drawing Figures PRESSURE SENSITIVE RECORDING SYSTEM AND METHOD OF PROVIDING A SPLIT IMAGE THEREFOR BACKGROUND OF THE INVENTION This invention relates to pressure-sensitive recording systems and methods, and more particularly to an improved system of the so-called carbonless type wherein capsules on one sheet containing one liquid reactant are ruptured by pressure to produce a chemical reaction with a co-reactant on another sheet to provide visible images on both such sheets as a result of a partial transfer of the co-reactant as well as the reactant.

Numerous carbonless systems have heretofore been proposed involving encapsulated liquid dyes or reactants that, upon rupture of the capsules, create an image by release or physical transfer of the colored dye or by chemical reaction of the encapsulated reactant with a co-reactant on the same or an adjacent surface. But in each of these systems, insofar as is known, the co-reactant never transfers. Hence, in a self-contained system (i.e., both reactants on the same surface), no imaging occurs on an adjacent surface because no coreactant is transferred; any encapsulated reactant released to the adjacent surface thus has no co-reactant to react with to form an image. Similarly, in a two-sheet system (i.e., reactant and coreactant on adjacent surfaces), only reactant that transfers to the co-reactant coated sheet will form an image on the latter; since no co-reactant transfers, any reactant remaining in situ has no co-reactant to react with to form an image on the capsule-containing surface.

In one pressure-sensitive recording system heretofore proposed, an encapsulated colorless marking material is coated on the underside of a porous sheet having a reactive coating on its upper side. When a stylus or the like applies pressure to said upper side, the capsules rupture causing marking material to bleed up through the porous sheet and react with the reactive coating to produce a right-readable image on said top side. If and when a receiving sheet with a reactive coating is disposed adjacent the encapsulated underside of the porous sheet, a chemical reaction will also occur to provide an image on the top of the receiving sheet. Thus, when compressed, the porous sheet releases a reactant that migrates up through the sheet to make a one-way reaction with a reactive coating at the top of the sheet and a one-way reaction with the adjacent reactively coated surface of another sheet. However, the colorless marking material produces no image on the underside of the porous sheet.

In another system, an image is produced concurrently on the adjacent surfaces of two superposed sheets; but in such system the underside of a porous upper sheet is coated with an encapsulated colored marking fluid or colored dye. In such event the images are formed, not by any chemical reaction, but by capsule rupture and release of colored ink or dye in the upper sheet and oneway physical transfer of some of such colored ink or dye to the lower sheet.

While these arrangements may be interesting in theory, they have several disadvantages in practice. Any inadvertent rupture of the colored-dye-containing capsules prior to superposition of the sheets will produce undesirable marking or smearing. Also, the material used to coat the sheet must provide a low-viscosity ink comprising a solvent capable of penetrating that sheet in such manner and in such quantity as to provide a visible colored mark or a potentially visible mark on the side opposite the coated side. The solvent must be suffi- 5 ciently volatile to limit the migration. Volatile solvents are difficult to retain in capsules. Moreover, the low viscosity inks will feather out laterally, as well as vertically, as they bleed through the porous sheet; and this will impair legibility and sharpness of the resultant image on the porous sheet.

SUMMARY OF THE INVENTION Applicants have found that these and other problems can be overcome by providing a pressure-sensitive recording system and method embodying an encapsu lated reactant in solution that partially transfers and reacts with a co-reactant that also partially transfers upon rupture of the capsules so as to simultaneously produce a dry right-readable reaction by-product colored image anda dry reaction by-p ro d uct colored mirror image thereof on adjacent surfaces of two sheets as a result of the two-way mutual physical transfer and chemical reaction. The encapsulated reactant and the co-reactant are supported on adjacent surfaces of different sheets. Only some of the co-reactant and some of the reactant physically transfer to the adjacent surface of the other sheet; the balance remains in situ (i.e., on the surface on which it had originally been supported), thus providing colored images by essentially identical chemical reactions on both such surfaces.

Such a pressure-responsive recording system is especially desirable in record sets, such as used for gasoline credit sales, wherein a translucent sheet overlies an opaque sheet; in such case, the encapsulated reactant would preferably be applied to the opaque sheet and the coreactant applied to the translucent sheet.

Other objects and advantages of the invention will become more apparent from the following detailed description and from the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIGS. 1 and 2 are elevational sectional views, to vastly enlarged scale, of a pressure-sensitive recording system embodying the invention and comprising an encapsulated reactant and co-reactant coated on adjacent surfaces of different sheets, FIG. 1 denoting the condition before and FIG. 2 the condition after a mutual partial transfer of reactant and co-reactant produces chemical reactions and corresponding images on both such surfaces.

DESCRIPTION OF PREFERRED EMBODIMENT The pressure-sensitive recording system illustrated in FIGS. 1 and 2 comprises a substrate, such as sheet 10, the upper surface of which has a coating 11 or the like.

This coating includes a multitude of microscopic pressure-rupturable capsules 12 containing a reactant solution comprising a chemically reactive dye precursor and a solvent. Above coating 11 is a coating 13 or the like which comprises a color-forming co-reactant for the said dye precursor and is carried by the underside of an overlying substrate, such as a sheet 14.

According to the invention, when sheets It), 14 are superimposed with reactant coating 11 and co-reactant coating 13 in intimate physical contact, a concurrent partial release of the reactant solution and co-reactant coating will occur when the capsules 12 are ruptured by application of sufficient localized pressure, for example to the upper side of sheet 14. by a stylus, imprint member or the like that exerts at least a preselected magnitude of impact or shear force. Thus. the cobe ofa formulation providing sufficient adhesion to the substrate 14 and cohesion within itself to prevent premature release during normal handling; it must exhibit the proper amount of adhesion to coating 12 to facilireactant coating 13 transferred to sheet 10 chemically tate transfer; and yet coating 13 must have a cohesion reacts with that portion of the released reactant solulow gh to as e that hen a normal degree of lotion which remained in sit on said h t t produce a calized pressure is applied, the forces of adhesion will dry right-reading reaction by-product image 15 correprevail over the forces of cohesion. This combination sponding to the pattern of applied pressure. Meanof chemical reaction characteristics and adhesion/- while, the released reactant solution transferred to Cohesion Characteristics mUSt as e that approxisheet 14 chemically reacts with the nontransferred pormately half of the co-reactant coating will transfer and tion of co-reactant coati 13 t produce Simultathe balance will remain in situ to produce split imneously on the underside of said sheet a dry reaction g 0f n ially qual intensity by essentially by-product mirror ima 16 f th i a 15 d d identical chemical reactions on both adjacent surfaces. on sheet 10. Hence, two corresponding split images 15 The (to-reactant coating 13 is preferably applied by a 15, 16 will b d d concurrently on dj t conventional coating apparatus before the paper web faces of both sheets l0, 14 by the two-way mutual pariS Severed o ee 14- tial physical transfer and chemical interaction of reac- NOW at t e general nature Of the invention has tant and co-reactant. been described, the following examples are presented When the pressure-sensitive r di g di i a 20 as illustrative of the encapsulated reactants and the coset used for gasoline credit sales or the like, the overlyeactants that have been used successfully in appliing sheet 14 is preferably sufficiently transparent (e.g., cants split image pressure-sensitive recording systranslucent) so that the mirror image provided on the e and methodunderside of said sheet will be viewable from the top EXAMPLES side of the sheet as a right-reading image when the in each of the following tabulated Examples 1-6, a sheets l0, 14 are separated. This desirably permits the 200 CB (Coated Back) sheet of Action paper localized pressure to be applied by a noninked pressure marketed by Minnesota Mining and Manufacturing roller via an embossed credit card, since no right- Company was used to constitute the substrate 10 and readable image need be imprinted from the credit card encapsulated coating 11. While the specific formulaonto the upper surface of sheet 14. tion of said coating has not been disclosed by said com- The pressure-rupturable capsules 12 may be formed pany, e cap ules 12 form ng pa t thereof are known from any film forming material that is sufficiently to contain dithiooxamide or one of its N,N-distrong to preclude inadvertent rupture. While many substituted derivatives dissolved in an organic solvent, materials might be satisfactory, aldehyde condensation as taught in U.S. Pat. No. 3,481,759. Based upon a curpolymers, especially urea formaldehyde condensation sory analysis, the capsules are believed to contain solpolymers, are especially suitable. The capsules are vents of tributyl phosphate and diethyl phthalate and preferably from about 1 to 50 microns in size and reactive components of N,N-bis(2-octanoyloxyethyl) formed in any suitable manner already known in the dithiooxamide coated with a binder containing a zincart; e.g., in the manner described in U.S. Pat. No. carboxylate; and the capsule walls are formed of urea 2,730,457; 3,432,327; 3,5l6,846; or 3,558,341. The formaldehyde resin. capsules contain a liquid reactant precursor; preferably The co-reactant coatings 13 were prepared by adding this is in the form of a solution comprising a chemically the ingredients specified in Table l to a suitab e o reactive dye precursor dissolved in a volatile solvent. A preferably denatured alcohol such as that designated as particularly suitable class of reactant precursors are di- PM 3163 and marketed by Ashland Chemical Co. Each thiooxamide and its N,N-di-substituted derivatives; of mixture was then shaken for 15 minutes on a vibratory these, the N,N-diorgano-substituted-dithiooxamides, paint shaker using steel balls within the container to fadissolved in organic solvents, are preferred. it will be cilitate solution and dispersion. The resulting solution understood that the solution will preferably contain was then applied as a coating to an ll-pound one or more additional ingredients for specialized pur- (l7 22500) translucent paper substrate and dried to poses such as enhancing storage stability, speed and/or remove the solvent. intensity of color-producing reaction, etc. The variously coated papers were then incorporated Applicants improvement resides, primarily, in prointo respective manifold sets so that the co-reactantviding a co-reactant coating 13 that will partially transcoated surface was face down in intimate physical fer in response to localized pressure and concurrently contact with the encapsulated face-up coating on the chemically react with the particular reactant solution 3M CB sheet. These sets were than imaged by applying released from the capsules 12 to promptly produce an localized pressure using well known techniques such as image of commercially acceptable intensity and duraball-point pens, pencils, and imprinting devices embility. This involves providing a co-reactant coating 13 ploying embossed credit cards. that not only produces the desired reaction product Table l expresses the formulations of the co-reactant when it reacts chemically with the particular reactant coatings 13 of Examples 1 through 6 in terms of perin the capsule 12, but also exhibits proper adhesion/- eentage by weight of the various ingredients less the cohesion characteristics. That is, the coating 13 must volatile solvent which ultimately evaporates.

Table I Examples Ingredients 1 4 5 6 Nickel (II) 30.8 36.2 32.3 30.8 32.3 22.3 chloride Table l-Continued Fx'imnles lngredients l 2 3 4 5 6 Zinc resinate 15.4 14.6 16.2 9.2 20.8 18.5 Lithium 38.4 43.8 36.i 44.6 31.5 40.7

stearate Sodium 15.4 5.4 15.4 15.4 15.4 18.5 benzoate In the above formulations, it was found that the various ingredients serve the following functions: The nickel (ll) chloride provides the metal cation that ultimately complexes with dithiooxamide and/or its derivatives. The zinc resinate provides a substance that reacts with the nickel chloride to form (in part) nickel resinate which is highly soluble in the solvent system included in the capsule fill of the 3M CB sheet; it also binds the coating to the substrate and provides coating cohesion. The lithium stearate causes a reasonably bal- 2Q anced split of the image between the mating sheets, provides coating cohesion and increased image intensity, and also renders the applied coating semi-opaque to increase image contrast. The three ingredients just specified are very important in assuring the split image according to the invention; whereas the sodium benzoate is considered highly desirable, though not essential,

because it improves environmental image stability.

The six formulations of Examples 1-6 were found to exhibit the following functional requirements that are 3 essential to commercial acceptability; good image visual intensity on both plies, good imaging speed, and good environmental stability. They were also found suitable for imaging by either pens or credit card imprinters. 3 5

The formulation that produces the optimum blend of the aforementioned functional requirements necessary for commercial acceptance was that of Example 1, which is therefore repeated below as the preferred formulation. However, it appears, based upon an evaluation of these listed examples and others, that commercially acceptable (though not necessarily optimum) coreactant coatings may be obtained by employing the named ingredients within the ranges specified below:

"lngrcdicnts, in percent by weight, but less solvent.

While applicants do not know the precise reason why the specific formulation of Example 1 is superior to that of the others, they believe, on the basis of their findings, that it possesses the optimum balance of adhesion/cohesion forces and chemical reactivity.

As above indicated, the formulations above listed in Examples l-6 do not constitute all of the formulations prepared and evaluated. Other formulations were prepared and evaluated which included one or more of the ingredients listed for Examples l-6, together with nickel resinate, nickel stearate, stearic acid, and others in varying amounts; but the evaluations made on such other formulations showed that they were generally unsuitable for commercial acceptability, except for one formulation in which silica and sodium benzoate were included. However, the silica merely supplemented and served the same function as the lithium stearate in enhancing image contrast in the translucent sheet 14, but it could not replace the lithium stearates function of also increasing image intensity.

It should be noted, however, that applicants pressure-sensitive recording system and method is not limited to use of the specific encapsulated reactant em ployed in the above-described CB sheets marketed by 3M. Applicants have successfully achieved split imaging by mutual physical transfer of reactant and coreactant and mutual chemical reaction in carbonless The following formulation was applied as the coating 13 on translucent sheet 14:

(Wet) (Dry) lngredient Parts by Weight 7: by Weight Zinc resinate 3.0 27.3 Propyl gallate 3.0 27.3 Tannic acid 1.0 9.1 Colloidal silica 4.0 36.3 Toluene 30.0 Denatured alcohol 10.0

Evaporated during drying.

When these coatings ll, 13 were placed in intimate contact and capsules 12 were ruptured by localized pressure in the manner already described, a split image (though not necessarily optimized) mutual transfer and chemical reaction were achieved. In this formulation, the zinc resinate serves as the binder; the propyl gallate and tannic acid serve as the co-reactant for the encapsulated precursor; and the silica facilitates a splitting of the image between the mating sheets and also renders the coating semi-opaque thereby increasing image contrast.

EXAMPLE 8 An encapsulated donor sheet currently being offered for sale in the United States by The Pilot Pen Company, Ltd., Tokyo, Japan, was used to constitute the substrate 10 and encapsulated coating 11. While the specific formulation of the encapsulated coating is not known, it is believed to be in accord with the teachings of Exampie 3 of U.S. Pat. No. 3,432,327.

The following formulation was applied as the coating 13 on translucent sheet 14:

ingredient Parts by Weight (Wet) /1 by Weight (D y) Marketed by GAF Corporation Marketed by Commercial Solvents Corp. '"Markcted by W. R. Grace Corp. "Evaporated during drying.

in this formulation, the propyl gallate and tannic acid serve as the co-reactant for the encapsulated precursor; the polyvinylpyrrolidone and to some extent the waxes serve as the binder; and the waxes and the silica facilitate splitting of the image, with the silica also serving to enhance image contrast.

An acceptable (though not necessarily optimized) split image reaction was observed when the coatings ll, 13 were placed in intimate contact and the capsules 12 were ruptured by localized pressure in the manner already described. The images made using a ball-point pen were dark and formed rapidly, although those made with a credit card imprinter resulted in a somewhat less intense image than desired on the encapsulated donor sheet 14. This coating was found to exhibit reasonably good environmental stability.

From the foregoing it will be seen that applicants have demonstrated that a pressure-induced mutual two-way partial transfer of reactant and co-reactant from adjacent surfaces will provide, by essentially identical chemical reactions on both said surfaces, a legible image and a mirror image thereof; and that when the mirror image is thus provided on the underside of a translucent sheet, it may be viewed as a right-readable image from the top of such translucent sheet. This desirably eliminates the need for imprinting with an inked roll or the like on the upper sheet of a two-sheet set.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be apparent that the foregoing and other various changes may be made in the pressure-sensitive recording system and in the specified formulations and method without departing from the spirit, scope and teaching of the present invention. Accordingly, the system and method herein disclosed are to be considered merely as illustrative, and the scope of the invention is to be limited only as specified in the claims.

What is claimed is:

l. A pressure-sensitive recording system comprising one sheet having a surface supporting a multitude of microscopic pressure-rupturable capsules containing a reactant solution comprising a chemically reactive dye precursor and a solvent, and

different sheet having a surface supporting a partially releasable co-reactant adapted, upon application of a localized pressure to the sheets and consequent rupture of the capsules while the surfaces are superimposed in intimate contact, to cause some of the co-reactant and some of the capsules and reactant solution to remain in situ on their respective supporting surfaces and the remainder of each to physically transfer to the adjacent supporting surface of the respective other sheets, thereby to cause essentially identical chemical reactions to occur between precursor and co-reactant concurrently on said surfaces for simultaneously providing at least one right-readable image on one of said surfaces and a mirror image thereof on the other of said surfaces,

the particular one of said sheets having said other of said surfaces being sufficiently transparent so that upon separation of the sheets the mirror image will be viewable as a right readable image from the reverse side of such particular sheet without bleed through of reaction product to said reverse side.

2. A system according to claim 1, the reactant solution comprising a precursor taken from the class of dithiooxamide and its N,Ndi-substituted derivatives, and the co-reactant comprising by weight, when dried, about 22-37 percent nickel (Il) chloride; about 9-21 percent zinc resinate; about 31-45 percent lithium stearate; and about 5-19 percent sodium benzoate.

3. A system according to claim 1, wherein the co reactant comprises by weight, when dried, essentially about 55 percent propyl gallate; 6 percent tannic acid; 6 percent polyvinylpyrrolidone; 16 percent oxazoline wax; and 17 percent silica.

4. A system according to claim 1, wherein the coreactant comprises by weight, when dried, essentially about 27 percent zinc resinate; 27 percent propyl gallate; 9 percent tannic acid; and 37 percent colloidal sil- 5. A system according to claim 1, wherein the solution comprises a precursor taken from the class of dithiooxamide and its N,Ndi-substituted derivatives, and the co-reactant comprises nickel (ll) chloride, zinc resinate, lithium stearate and sodium benzoate.

6. A system according to claim 1, wherein the coreactant comprises by weight, when dried, 22-37 percent nickel (ll) chloride; 9-21 percent zinc resinate; 31-45 percent lithium stearate; and 5-19 percent sodium benzoate.

7. A system according to claim 1, wherein the solution comprises a precursor taken from the class of dithiooxamide and its N,Ndi-substituted derivatives, and the co-reactant comprises by weight, when dried, essentially about 31 percent nickel (ll) chloride; 15 percent zinc resinate; 39 percent lithium stearate and 15 percent sodium benzoate. 

1. A PRESSURE-SENSITIVE RECORDING SYSTEM COMPRISING ONE SHEET HAVING A SURFACE SUPPORTING A MULTITUDE OF MICROSCOPIC PRESSURE-RUPTURABLE CAPSULES CONTAINING A REACTANT SOLUTION COMPRISING A CHEMICALLY REACTIVE DYE PRECURSOR AND A SOLVENT, AND A DIFFERENT SHEET HAVING A SURFACE SUPPORTING A PARTIALLY RELEASABLE CO-REACTANT ADAPTED, UPON APPLICATION OF A LOCALIZED PRESSURE TO THE SHEETS AND CONSEQUENT RUPTURE OF THE CAPSULES WHILE THE SURFACES ARE SUPERIMPOSED IN INTIMATE CONTACT, TO CAUSE SOME OF THE CO-REACTANT AND SOME OF THE CAPSULES AND REACTANT SOLUTION TO REMAIN IN SITU ON THEIR RESPECTIVE SUPPORTING SURFACES AND THE REMAINDER OF EACH TO PHYSICALLY TRANSFER TO THE ADJACENT
 2. A system according to claim 1, the reactant solution comprising a precursor taken from the class of dithiooxamide and its N,N''di-substituted derivatives, and the co-reactant comprising by weight, when dried, about 22-37 percent nickel (II) chloride; about 9-21 percent zinc resinate; about 31-45 percent lithium stearate; and about 5-19 percent sodium benzoate.
 3. A system according to claim 1, wherein the co-reactant comprises by weight, when dried, essentially about 55 percent propyl gallate; 6 percent tannic acid; 6 percent polyvinylpyrrolidone; 16 percent oxazoline wax; and 17 percent silica.
 4. A system according to claim 1, wherein the co-reactant comprises by weight, when dried, essentially about 27 percent zinc resinate; 27 percent propyl gallate; 9 percent tannic acid; and 37 percent colloidal silica.
 5. A system according to claim 1, wherein the solution comprises a precursor taken from the class of dithiooxamide and its N,N''di-substituted derivatives, and the co-reactant comprises nickel (II) chloride, zinc resinate, lithium stearate and sodium benzoate.
 6. A system according to claim 1, wherein the co-reactant comprises by weight, when dried, 22-37 percent nickel (II) chloride; 9-21 percent zinc resinate; 31-45 percent lithium stearate; and 5-19 percent sodium benzoate.
 7. A system according to claim 1, wherein the solution comprises a precursor taken from the class of dithiooxamide and its N,N''di-substituted derivatives, and the co-reactant comprises by weight, when dried, essentially about 31 percent nickel (II) chloride; 15 percent zinc resinate; 39 percent lithium stearate and 15 percent sodium benzoate. 